void test_plotting() {

  //TCanvas * can = new TCanvas("can", "", 800, 600);
  
  TFile * fin = new TFile("test.root");
  TH3D * h3d = (TH3D*)h3d;
  h3d->SetTitle("; x; y; z");
  gStyle->SetCanvasPreferGL(1);
  h3d->Draw("glcolz");
  double * x = new double[3];
  double * y = new double[3];
  double * z = new double[3];

  x[0] = 4600;
  x[1] = 4700;
  x[2] = 4800;

  y[0] = 3200;
  y[1] = 3300;
  y[2] = 3600;

  z[0] = 3600;
  z[1] = 3800;
  z[2] = 3900;

  gPad->Update();
  Double_t bm = gPad->GetBottomMargin();
  Double_t lm = gPad->GetLeftMargin();
  Double_t rm = gPad->GetRightMargin();
  Double_t tm = gPad->GetTopMargin();
  Double_t x1 = h3d->GetXaxis()->GetXmin();
  Double_t y1 = h3d->GetYaxis()->GetXmin();
  Double_t z1 = h3d->GetZaxis()->GetXmin();
  Double_t x2 = h3d->GetXaxis()->GetXmax();
  Double_t y2 = h3d->GetYaxis()->GetXmax();
  Double_t z2 = h3d->GetZaxis()->GetXmax();
  
  TPad * pad = new TPad("pad", "", 0., 0., 1, 1);
  pad->SetFillStyle(0);
  pad->SetFrameFillStyle(0);
  pad->Draw();
  pad->cd();
  pad->Range(x1-(x2-x1)*(lm/(1-rm-lm)),
 	     y1-(y2-y1)*(bm/(1-tm-lm)),
	     x2+(x2-x1)*(rm/(1-rm-lm)), 
	     y2+(y2-y1)*(tm/(1-tm-lm)));
  
  TH3D* h3d_clone = (TH3D*) h3d->Clone();
  h3d_clone->SetTitle("; x; y; z");
  //h3d_clone->Draw();
  TGraph2D * g= new TGraph2D(3, x, y, z);
  g->SetMarkerStyle(20);
  g->Draw("p");
  g->GetXaxis()->SetLimits(x1, x2);
  g->GetYaxis()->SetLimits(y1, y2);
  g->GetHistogram()->SetMinimum(z1);
  g->GetHistogram()->SetMaximum(z2);
  g->GetXaxis()->SetLabelSize(0);
  g->GetYaxis()->SetLabelSize(0);
  g->GetZaxis()->SetLabelSize(0);
  
  g->GetXaxis()->SetTickLength(0);
  g->GetYaxis()->SetTickLength(0);
  g->GetZaxis()->SetTickLength(0);
  
  double margin1 = 0.158;
  double margin2 = 0.114;
  pad->SetLeftMargin(margin1);
  pad->SetRightMargin(margin1);
  pad->SetTopMargin(margin2);
  pad->SetBottomMargin(margin2);
  pad->Update();
  pad->Modified();
  
  gPad->Update();
  
}